Substrates having improved crockfastness

ABSTRACT

An ink-printed substrate comprising a substrate and water-based ink composition printed on the substrate, wherein the ink-printed substrate has an average color density of at least about 0.48 or greater.

FIELD OF THE INVENTION

The present invention relates to the printing of substrates with an inkcomposition comprising a water-based ink. Specifically, the presentinvention relates to printed substrates webs that are printed with awater-based ink resulting in improved crockfastness.

BACKGROUND OF THE INVENTION

The printing of substrates, such as woven and nonwoven fabrics andfilms, is well known. The printing of fabrics with inks and dyes is acommon and widely used method for imparting patterns and colors to abasic fabric. Many current products, such as diapers and training pants,include printed designs to improve their appearance. A problem with suchprinted products is that the printed design can be smeared or evenremoved during the handling of products during manufacturing, packaging,and use.

Pigmented inks are beneficial for use on substrates because they tend tobe more resistant to leaching and mechanical rubbing than dye-based inksand thus tend to be more resistant to being removed from the surface ofsubstrates. Pigment-based inks also have better optical density per unitweight (better “mileage”) than dye-based inks, meaning that lesspigment-based ink is required to create the intensity of color. However,adhesive components are necessary to use along with pigmented inks toprevent removal of the pigment from the surface by mechanical abrasionor chemical leaching.

The industrial importance of pigment-based inks has increased in recenttimes. This is driven, in part, by the development of many new syntheticsubstrates that are incapable of being printed with conventionalsolvent-based or water-based inks, and consumers' preferences that theirgoods be printed with brand identifiers, aesthetically pleasing designsor functional markings. In order to adapt pigment-based inks for use ina variety of applications, namely low surface tension substrates, othershave employed high loads of volatile organic compounds (“VOC's”),thereby reducing the static and dynamic surface tension of the inks.However, volatile organic compounds such as alcohols, esters, ketones,aromatics and aliphatics create environmental hazards in theirproduction, disposal and use. They are also expensive. One example of anink used on an a low surface tension substrate is set forth in U.S. Pat.No. 5,458,590 to Schleinz et al., which employs a solvent blend toimpart the desired surface tension to the ink.

It has also been recognized that adding small amounts of wax to apolymer adhesive improves the dry rub properties. This is set forth inU.S. Pat. No. 5,458,590 to Schlienz et al, which shows using 0.5-5.0%wax, and in USPA 2007/0100025A1 to Steiner et al, which shows using 0.1to 2.0% waxes.

Still others have devised methods to adhere ink to low surface tensionsubstrates, such as surface pre-treatment via corona dischargetreatment, plasma treatment or use of a primer, as set forth in USPA2006/0246263 to Yahiaoui et al.

For an ink to be useful, it needs to be in a medium capable of bindingwith a substrate, either chemically or physically. Where physicalbinding is desirable, the ink's medium may have adhesivecharacteristics, and may be somewhat flexible to withstand distortionsof the substrate. The flexibility of an aqueous polymer is typicallyexpressed as its glass transition temperature, or Tg. Lower Tg'sgenerally correlate to greater elongation without fracturing. Theelongation property is significant in adhesive and coloring because theflexibility/elongation of a formula's polymer affects rub resistance.Specifically, flexibility and softness associated with lower Tg polymersprovide a high degree of grab and tack, which is expressed as a highcoefficient of friction (CoF). The higher the CoF, the more likely thepolymer is to “grab onto” and be “abraded off by” some other substrateor surface, thereby lowering the composition's dry rub resistance. Thus,in conventional inks, the desirable properties of adhesion andflexibility are at the expense of rub resistance. Alternatively,improving rub resistance conventionally creates adhesion and flexibilityproblems.

Thus, there remains a need for a substrate having improved crockfastnessthrough the use of a water-based ink which is environmentally friendly.There remains a need for a water-based ink that is useful on a varietyof substrates including those with low surface tensions, which hasdesirable wet and dry rub properties, resulting in improvedcrockfastness of substrates.

SUMMARY OF THE INVENTION

The present invention relates to an ink-printed substrate comprising asubstrate and water-based ink composition printed on the substrate,wherein the ink-printed substrate has an average color density of atleast about 0.48 or greater. In some embodiments of the presentinvention, the substrate may be a non-woven fibrous web. In someembodiments of the present invention, the substrate may have a lowsurface tension. In some embodiments of the present invention, thewater-based ink composition may comprise a low Tg° C. water-basedpolymer component. In some embodiments of the present invention, thesubstrate may be corona treated prior to application of the inkcomposition. In some embodiments of the present invention, an over printvarnish may be applied after the ink composition has been applied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a diaper in accordance with an embodiment ofthe present invention.

FIG. 2 is a cross sectional view of the diaper shown in FIG. 1 takenalong the sectional line 2-2 of FIG. 1.

FIG. 3 is a partial cross sectional view of an absorbent core layer inaccordance with an embodiment of this invention.

FIG. 4a is a partial sectional view of an absorbent core comprising acombination of the first and second absorbent core layers.

FIG. 4b is a partial sectional view of an absorbent core comprising acombination of the first and second absorbent core layers.

DETAILED DESCRIPTION OF THE INVENTION

The present invention concerns the printing of substrates with an inkcomposition comprising a water-based ink. Specifically, the substratesare useful in an absorbent article, such as a diaper.

As used herein, the following terms have the following meanings:

“Absorbent article” refers to devices that absorb and contain bodyexudates, and, more specifically, refers to devices that are placedagainst or in proximity to the body of the wearer to absorb and containthe various exudates discharged from the body. Absorbent articles mayinclude diapers, training pants, adult incontinence undergarments,feminine hygiene products, breast pads, care mats, bibs, wound dressingproducts, and the like. As used herein, the term “body fluids” or “bodyexudates” includes, but is not limited to, urine, blood, vaginaldischarges, breast milk, sweat and fecal matter.

“Absorbent core” means a structure typically disposed between a topsheet and cover sheet of an absorbent article for absorbing andcontaining liquid received by the absorbent article and may comprise oneor more substrates, absorbent polymer material disposed on the one ormore substrates, and a thermoplastic composition on the absorbentparticulate polymer material and at least a portion of the one or moresubstrates for immobilizing the absorbent particulate polymer materialon the one or more substrates. In a multilayer absorbent core, theabsorbent core may also include a cover layer. The one or moresubstrates and the cover layer may comprise a nonwoven. Further, theabsorbent core may be substantially cellulose free. The absorbent coredoes not include an acquisition system, a top sheet, or a back sheet ofthe absorbent article. In a certain embodiment, the absorbent core wouldconsist essentially of the one or more substrates, the absorbent polymermaterial, the thermoplastic composition, and optionally the cover layer.

“Airfelt” is used herein to refer to comminuted wood pulp, which is aform of cellulosic fiber.

“Colorant” includes one or more of pigments and or dyes; colorant mayfurther include an acrylic colloidal dispersion, acrylic solution, orsurfactants and water.

“Color density” and “Optical Density” refer to a unitless value whichrefers to the vibrancy of the ink printed unto a substrate. Data derivedherein is based on a Gretag/Macbeth SpectroEyespectrophotometer/Densitometer for measurements.

“Color transfer” refers to how much ink is rubbed off from a givensample. Data derived herein is based on the CIE Color System using aHunter Color LabscanXE color spectrophotometer to measure the amount ofcolor transferred to another substrate.

“Comprise,” “comprising,” and “comprises” are open ended terms, eachspecifies the presence of what follows, e.g., a component, but does notpreclude the presence of other features, e.g., elements, steps,components known in the art, or disclosed herein.

“Consisting essentially of” is used herein to limit the scope of subjectmatter, such as that in a claim, to the specified materials or steps andthose that do not materially affect the basic and novel characteristicsof the subject matter.

“Crockfastness” and “crockfastness rating” shall refer to rubresistance, expressed on a scale of 0 to 5, with 5 showing no sign ofcolor transfer. Crockfastness data reported herein is determined using acertified AATCC Rotary Vertical Crockmeter, Model M238E, supporting awhite cloth substrate and rubbing in a reciprocal back and forthcircular motion while applying 7.62 pounds per square inch to a printedsubstrate. Because of its severity, this test equipment is the generallyaccepted method for measuring rub resistance in the carpet and textileindustries.

“Disposable” is used in its ordinary sense to mean an article that isdisposed or discarded after a limited number of usage events overvarying lengths of time, for example, less than about 20 events, lessthan about 10 events, less than about 5 events, or less than about 2events.

“Diaper” refers to an absorbent article generally worn by infants andincontinent persons about the lower torso so as to encircle the waistand legs of the wearer and that is specifically adapted to receive andcontain urinary and fecal waste. As used herein, term “diaper” alsoincludes “pants” which is defined below.

“Fiber” and “filament” are used interchangeably.

“Glass Transition Temperature” generally refers to the temperature belowwhich a given polymer is physically similar to glass (particularly abreakable solid), and above which the polymer behaves as a liquid,albeit of high viscosity. Tg is an abbreviation for glass transitiontemperature, with Tg° C. referring to the glass transition temperatureexpressed in degrees Celsius. The Glass Transition Temperature ismeasured using ASTM Method D7028-07.

“Ink” and “composition” are used interchangeably herein; an ink orcomposition may or may not include a colorant.

A “low surface tension substrate”, used herein refers to a substrate forreceiving ink which exhibits a low surface tension and is thereforedifficult to print with conventional inks or methods. These substratesare typically hydrophobic, apolar and inert. Examples of such substratesinclude webs of polyolefin polymer nonwoven fibers found in syntheticcurtains and vertical blinds, feminine care products, diapers,incontinence pants, training pants and disposable wipes. Other examplesare continuous films of extruded polyolefin polymer substrates.

A “nonwoven” is a manufactured sheet, web or batt of directionally orrandomly orientated fibers, bonded by friction, and/or cohesion and/oradhesion, excluding paper and products which are woven, knitted, tufted,stitch-bonded incorporating binding yarns or filaments, or felted bywet-milling, whether or not additionally needled. Nonwovens may includehydroentangled nonwovens. The fibers may be of natural or man-madeorigin and may be staple or continuous filaments or be formed in situ.Commercially available fibers have diameters ranging from less thanabout 0.001 mm to more than about 0.2 mm and they come in severaldifferent forms: short fibers (known as staple, or chopped), continuoussingle fibers (filaments or monofilaments), untwisted bundles ofcontinuous filaments (tow), and twisted bundles of continuous filaments(yarn). Nonwoven fabrics can be formed by many processes such asmeltblowing, spunbonding, solvent spinning, electrospinning, andcarding. The basis weight of nonwoven fabrics is usually expressed ingrams per square meter (gsm).

“Pant” or “training pant”, as used herein, refer to disposable garmentshaving a waist opening and leg openings designed for infant or adultwearers. A pant may be placed in position on the wearer by inserting thewearer's legs into the leg openings and sliding the pant into positionabout a wearer's lower torso. A pant may be preformed by any suitabletechnique including, but not limited to, joining together portions ofthe article using refastenable and/or non-refastenable bonds (e.g.,seam, weld, adhesive, cohesive bond, fastener, etc.). A pant may bepreformed anywhere along the circumference of the article (e.g., sidefastened, front waist fastened). While the terms “pant” or “pants” areused herein, pants are also commonly referred to as “closed diapers,”“prefastened diapers,” “pull-on diapers,” “training pants,” and“diaper-pants”. Suitable pants are disclosed in U.S. Pat. No. 5,246,433,issued to Hasse, et al. on Sep. 21, 1993; U.S. Pat. No. 5,569,234,issued to Buell et al. on Oct. 29, 1996; U.S. Pat. No. 6,120,487, issuedto Ashton on Sep. 19, 2000; U.S. Pat. No. 6,120,489, issued to Johnsonet al. on Sep. 19, 2000; U.S. Pat. No. 4,940,464, issued to Van Gompelet al. on Jul. 10, 1990; U.S. Pat. No. 5,092,861, issued to Nomura etal. on Mar. 3, 1992; U.S. Patent Publication No. 2003/0233082 A1,entitled “Highly Flexible And Low Deformation Fastening Device”, filedon Jun. 13, 2002; U.S. Pat. No. 5,897,545, issued to Kline et al. onApr. 27, 1999; U.S. Pat. No. 5,957,908, issued to Kline et al on Sep.28, 1999.

“Polyurethane dispersion”, also known as PUD, is a polyurethane which isdispersed in water. Used herein, PUD refers to a catalyst containing,unblocked, fully reacted polyurethane water dispersion.

“Substantially cellulose free” is used herein to describe an article,such as an absorbent core, that contains less than 10% by weightcellulosic fibers, less than 5% cellulosic fibers, less than 1%cellulosic fibers, no cellulosic fibers, or no more than an immaterialamount of cellulosic fibers. An immaterial amount of cellulosic materialwould not materially affect the thinness, flexibility, or absorbency ofan absorbent core.

“Substantially continuously distributed”, as used herein, refers toabsorbent particulate polymer material that is arranged across theabsorbent particulate polymer material area. Optionally, the absorbentparticulate polymer material may be arranged such that the substratelayers do not touch in various zones. In one embodiment, the substratelayers may touch in the peripheral areas outside the absorbentparticulate polymer material area. It is important to note that thethermoplastic material used in the present invention does not interruptthe substantially continuously distributed absorbent particulate polymermaterial. Thus, the substantially continuously distributed absorbentparticulate polymer material includes the thermoplastic material.

“Substrate” includes any material that the inks of the present inventioncan be printed on. Thus, substrates of the present invention include,but are not limited to, non-wovens, films, fibrous polyolefin webs,polyolefin webs, cellulosic webs, elastomeric webs, laminates of one ormore of the above or any combination of one or more of the above.

“Synurine” refers to a synthetic urine sample, which is prepared bysolubilizing 2.0 g potassium chloride, 2.0 g sodium sulfate, 0.85 gammonium phosphate monobasic, 0.15 g ammonium phosphate dibasic, 0.25 gcalcium chloride dehydrate, and 0.50 g magnesium chloride hexahydrate in1 liter of distilled water.

“Thickness” and “caliper” are used herein interchangeably.

“Very low Tg° C.” used herein is about −82° C.

“Volatile organic compounds”, also known as VOC's, include alcohols,esters, ketones, aromatics and aliphatics.

“Wt %” refers to the percentage weight of a specific component relativeto the entire composition.

Absorbent Article

FIG. 1 is a plan view of a diaper 10 according to a certain embodimentof the present invention. The diaper 10 is shown in its flat out,uncontracted state (i.e., without elastic induced contraction) andportions of the diaper 10 are cut away to more clearly show theunderlying structure of the diaper 10. A portion of the diaper 10 thatcontacts a wearer is facing the viewer in FIG. 1. The diaper 10generally may comprise a chassis 12 and an absorbent core 14 disposed inthe chassis.

The chassis 12 of the diaper 10 in FIG. 1 may comprise the main body ofthe diaper 10. The chassis 12 may comprise an outer covering 16including a top sheet 18, which may be liquid pervious, and/or a backsheet 20, which may be liquid impervious. The absorbent core 14 may beencased between the top sheet 18 and the back sheet 20. The chassis 12may also include side panels 22, elasticized leg cuffs 24, and anelastic waist feature 26.

The leg cuffs 24 and the elastic waist feature 26 may each typicallycomprise elastic members 28. One end portion of the diaper 10 may beconfigured as a first waist region 30 of the diaper 10. The first waistregion 30 has a first edge 100. An opposite end portion of the diaper 10may be configured as a second waist region 32 of the diaper 10. Thesecond waist region 32 has a second edge 110. An intermediate portion ofthe diaper 10 may be configured as a crotch region 34, which extendslongitudinally between the first and second waist regions 30 and 32. Thewaist regions 30 and 32 may include elastic elements such that theygather about the waist of the wearer to provide improved fit andcontainment (elastic waist feature 26). The crotch region 34 is thatportion of the diaper 10 which, when the diaper 10 is worn, is generallypositioned between the wearer's legs.

The diaper 10 is depicted in FIG. 1 with its longitudinal axis 36 andits transverse axis 38. The periphery 40 of the diaper 10 is defined bythe outer edges of the diaper 10 in which the longitudinal edges 42 rungenerally parallel to the longitudinal axis 36 of the diaper 10 and theend edges 44 run between the longitudinal edges 42 generally parallel tothe transverse axis 38 of the diaper 10. The chassis 12 may alsocomprise a fastening system, which may include at least one fasteningmember 46 and at least one stored landing zone 48.

The diaper 20 may also include such other features as are known in theart including front and rear ear panels, waist cap features, elasticsand the like to provide better fit, containment and aestheticcharacteristics. Such additional features are well known in the art andare e.g., described in U.S. Pat. No. 3,860,003 and U.S. Pat. No.5,151,092.

In order to keep the diaper 10 in place about the wearer, at least aportion of the first waist region 30 may be attached by the fasteningmember 46 to at least a portion of the second waist region 32 to formleg opening(s) and an article waist. When fastened, the fastening systemcarries a tensile load around the article waist. The fastening systemmay allow an article user to hold one element of the fastening system,such as the fastening member 46, and connect the first waist region 30to the second waist region 32 in at least two places. This may beachieved through manipulation of bond strengths between the fasteningdevice elements.

According to certain embodiments, the diaper 10 may be provided with are-closable fastening system or may alternatively provided in the formof a pant-type diaper. When the absorbent article is a diaper, it maycomprise a re-closable fastening system joined to the chassis forsecuring the diaper to a wearer. When the absorbent article is apant-type diaper, the article may comprise at least two side panelsjoined to the chassis and to each other to form a pant. The fasteningsystem and any component thereof may include any material suitable forsuch a use, including but not limited to plastics, films, foams,nonwoven webs, woven webs, paper, laminates, fiber reinforced plasticsand the like, or combinations thereof. In certain embodiments, thematerials making up the fastening device may be flexible. Theflexibility may allow the fastening system to conform to the shape ofthe body and thus, reduce the likelihood that the fastening system willirritate or injure the wearer's skin.

For unitary absorbent articles, the chassis 12 and absorbent core 14 mayform the main structure of the diaper 10 with other features added toform the composite diaper structure. While the top sheet 18, the backsheet 20, and the absorbent core 14 may be assembled in a variety ofwell-known configurations, diaper configurations are described generallyin U.S. Pat. No. 5,554,145 entitled “Absorbent Article With MultipleZone Structural Elastic-Like Film Web Extensible Waist Feature” issuedto Roe et al. on Sep. 10, 1996; U.S. Pat. No. 5,569,234 entitled“Disposable Pull-On Pant” issued to Buell et al. on Oct. 29, 1996; andU.S. Pat. No. 6,004,306 entitled “Absorbent Article WithMulti-Directional Extensible Side Panels” issued to Robles et al. onDec. 21, 1999.

The top sheet 18 in FIG. 1 may be fully or partially elasticized or maybe foreshortened to provide a void space between the top sheet 18 andthe absorbent core 14. Exemplary structures including elasticized orforeshortened top sheets are described in more detail in U.S. Pat. No.5,037,416 entitled “Disposable Absorbent Article Having ElasticallyExtensible Top sheet” issued to Allen et al. on Aug. 6, 1991; and U.S.Pat. No. 5,269,775 entitled “Trisection Top sheets for DisposableAbsorbent Articles and Disposable Absorbent Articles Having SuchTrisection Top sheets” issued to Freeland et al. on Dec. 14, 1993.

The back sheet 26 may be joined with the top sheet 18. The back sheet 20may prevent the exudates absorbed by the absorbent core 14 and containedwithin the diaper 10 from soiling other external articles that maycontact the diaper 10, such as bed sheets and undergarments. In certainembodiments, the back sheet 26 may be substantially impervious toliquids (e.g., urine) and comprise a laminate of a nonwoven and a thinplastic film such as a thermoplastic film having a thickness of about0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils). Suitable back sheetfilms include those manufactured by Tredegar Industries Inc. of TerreHaute, Ind. and sold under the trade names X15306, X10962, and X10964.Other suitable back sheet materials may include breathable materialsthat permit vapors to escape from the diaper 10 while still preventingexudates from passing through the back sheet 10. Exemplary breathablematerials may include materials such as woven webs, nonwoven webs,composite materials such as film-coated nonwoven webs, and microporousfilms such as manufactured by Mitsui Toatsu Co., of Japan under thedesignation ESPOIR NO and by EXXON Chemical Co., of Bay City, Tex.,under the designation EXXAIRE. Suitable breathable composite materialscomprising polymer blends are available from Clopay Corporation,Cincinnati, Ohio under the name HYTREL blend P18-3097. Such breathablecomposite materials are described in greater detail in PCT ApplicationNo. WO 95/16746, published on Jun. 22, 1995 in the name of E. I. DuPont.Other breathable back sheets including nonwoven webs and aperturedformed films are described in U.S. Pat. No. 5,571,096 issued to Dobrinet al. on Nov. 5, 1996.

FIG. 2 shows a cross section of FIG. 1 taken along the sectional line2-2 of FIG. 1. Starting from the wearer facing side, the diaper 10 maycomprise the top sheet 18, the components of the absorbent core 14, andthe back sheet 20. According to a certain embodiment, diaper 10 may alsocomprise an acquisition system 50 disposed between the liquid permeabletop sheet 18 and a wearer facing side of the absorbent core 14. Theacquisition system 50 may be in direct contact with the absorbent core.The acquisition system 50 may comprise a single layer or multiplelayers, such as an upper acquisition layer 52 facing towards thewearer's skin and a lower acquisition 54 layer facing the garment of thewearer. According to a certain embodiment, the acquisition system 50 mayfunction to receive a surge of liquid, such as a gush of urine, andquickly absorb the liquid and distribute it across the absorbent core 14so that the absorbent core absorbs the liquid before the liquid flowsbeyond the absorbent layer 14 and out of the diaper 10. In other words,the acquisition system 50 may serve as a temporary reservoir for liquiduntil the absorbent core 14 can absorb the liquid.

The absorbent core 14 is disposed between the top sheet 18 and the backsheet 20 and comprises two layers, a first absorbent layer 60 and asecond absorbent layer 62. As shown in FIG. 3, the first absorbent layer60 of the absorbent core 14 comprises a substrate 64, an absorbentparticular polymer material 66 on the substrate 64, and a thermoplasticcomposition 68 on the absorbent particulate polymer material 66 and atleast portions of the first substrate 64 as an adhesive for covering andimmobilizing the absorbent particulate polymer material 66 on the firstsubstrate 64. According to another embodiment, the first absorbent layer60 of the absorbent core 14 may also include a cover layer on thethermoplastic composition 68.

Likewise, as illustrated in FIG. 2, the second absorbent layer 62 of theabsorbent core 14 may also include a substrate 72, an absorbentparticulate polymer material 74 on the second substrate 72, and athermoplastic composition 66 on the absorbent particulate polymermaterial 74 and at least a portion of the second substrate 72 forimmobilizing the absorbent particulate polymer material 74 on the secondsubstrate 72. Although not illustrated, the second absorbent layer 62may also include a cover layer such as the cover layer.

The substrate 64 of the first absorbent layer 60 may be referred to as adusting layer and has a first surface 78 which faces the back sheet 20of the diaper 10 and a second surface 80 which faces the absorbentparticulate polymer material 66. Likewise, the substrate 72 of thesecond absorbent layer 62 may be referred to as a core cover and has afirst surface 82 facing the top sheet 18 of the diaper 10 and a secondsurface 84 facing the absorbent particulate polymer material 74. Thefirst and second substrates 64 and 72 may be adhered to one another withadhesive about the periphery to form an envelope about the absorbentparticulate polymer materials 66 and 74 to hold the absorbentparticulate polymer material 66 and 74 within the absorbent core 14.

According to a certain embodiment, the substrates 64 and 72 of the firstand second absorbent layers 60 and 62 may be a non-woven material. Incertain embodiments, the non-wovens are porous and in one embodiment hasa pore size of about 32 microns.

As illustrated in FIGS. 3, 4 a, and 4 b, the absorbent particulatepolymer material 66 and 74 is deposited on the respective substrates 64and 72 of the first and second absorbent layers 60 and 62 in clusters 90of particles to form a grid pattern comprising land areas 94 andjunction areas 96 between the land areas 94. The junction areas 96 inthe grid pattern contain little or no absorbent particulate polymermaterial 66 and 74. The land areas 94 and junction areas 96 can have avariety of shapes including, but not limited to, circular, oval, square,rectangular, triangular, and the like.

The first and second absorbent layers 60 and 62 may be combined togetherto form the absorbent core 14 such that the grid patterns of therespective first and second absorbent layers 62 and 64 are offset fromone another along the length and/or width of the absorbent core 14. Therespective grid patterns may be offset such that the absorbentparticulate polymer material 66 and 74 is substantially continuouslydistributed across the absorbent particulate polymer area. In a certainembodiment, absorbent particulate polymer material 66 and 74 issubstantially continuously distributed across the absorbent particulatepolymer material area despite the individual grid patterns comprisingabsorbent particulate polymer material 66 and 74 discontinuouslydistributed across the first and second substrates 64 and 72 inclusters. In a certain embodiment, the grid patterns may be offset suchthat the land areas 94 of the first absorbent layer 60 face the junctionareas 96 of the second absorbent layer 62 and the land areas 94 of thesecond absorbent layer 62 face the junction areas 96 of the firstabsorbent layer 60. When the land areas 94 and junction areas 96 areappropriately sized and arranged, the resulting combination of absorbentparticulate polymer material 66 and 74 is a substantially continuouslayer of absorbent particular polymer material across the absorbentparticulate polymer material area of the absorbent core 14. In a certainembodiment, respective grid patterns of the first and second absorbentlayer 60 and 62 may be substantially the same.

In a certain embodiment, the amount of absorbent particulate polymermaterial 66 and 74 may vary along the length of the grid pattern. In acertain embodiment, the grid pattern may be divided into any number ofzones, in which the amount of absorbent particulate polymer material 66and 74 varies from zone to zone. The amount of absorbent particulatepolymer material 66 and 74 may, in a certain embodiment, graduallytransition from one of the plurality of absorbent zones to another. Thisgradual transition in amount of absorbent particulate polymer material66 and 74 may reduce the possibility of cracks forming in the absorbentcore 14.

The amount of absorbent particulate polymer material 66 and 74 presentin the absorbent core 14 may vary, but in certain embodiments, ispresent in the absorbent core in an amount greater than about 80% byweight of the absorbent core, or greater than about 85% by weight of theabsorbent core, or greater than about 90% by weight of the absorbentcore, or greater than about 95% by weight of the core. In a particularembodiment, the absorbent core 14 consists essentially of the first andsecond substrates 64 and 72, the absorbent particulate polymer material66 and 74, and the thermoplastic adhesive composition 68 and 76. In anembodiment, the absorbent core 14 may be substantially cellulose free.

In certain embodiments which are not substantially cellulose free, theabsorbent core 14 can include some amount of cellulose fiber material,such as airfelt. A relatively low amount of cellulosic material is used,in certain embodiments, less than 40 weight percent, or 20 weightpercent of cellulosic material, as compared to the weight of absorbentcore.

Exemplary absorbent structures for use as the absorbent assemblies aredescribed in U.S. Pat. No. 4,610,678 (Weisman et al.); U.S. Pat. No.4,834,735 (Alemany et al.); U.S. Pat. No. 4,888,231 (Angstadt); U.S.Pat. No. 5,260,345 (DesMarais et al.); U.S. Pat. No. 5,387,207 (Dyer etal.); U.S. Pat. No. 5,397,316 (LaVon et al.); and U.S. Pat. No.5,625,222 (DesMarais et al.).

The thermoplastic material 68 and 76 may serve to cover and at leastpartially immobilize the absorbent particulate polymer material 66 and74. In one embodiment of the present invention, the thermoplasticmaterial 68 and 76 can be disposed essentially uniformly within theabsorbent particulate polymer material 66 and 74. However, in a certainembodiment, the thermoplastic material 68 and 76 may be provided as afibrous layer which is at least partially in contact with the absorbentparticulate polymer material 66 and 74 and partially in contact with thesubstrate layers 64 and 72 of the first and second absorbent layers 60and 62. FIGS. 3, 4 a, and 4 b show such a structure, and in thatstructure, the absorbent particulate polymer material 66 and 74 isprovided as a discontinuous layer, and a layer of fibrous thermoplasticmaterial 68 and 76 is laid down onto the layer of absorbent particulatepolymer material 66 and 74, such that the thermoplastic material 68 and76 is in direct contact with the absorbent particulate polymer material66 and 74, but also in direct contact with the second surfaces 80 and 84of the substrates 64 and 72, where the substrates are not covered by theabsorbent particulate polymer material 66 and 74. This imparts anessentially three-dimensional structure to the fibrous layer ofthermoplastic material 68 and 76, which in itself is essentially atwo-dimensional structure of relatively small thickness, as compared tothe extension in length and width directions. In other words, thethermoplastic material 68 and 76 undulates between the absorbentparticulate polymer material 68 and 76 and the second surfaces of thesubstrates 64 and 72.

According to certain embodiments, the thermoplastic material 68 and 76can comprise any thermoplastic material, including, but not limited toadhesive thermoplastic materials, also referred to as hot meltadhesives. Some initially thermoplastic materials may later lose theirthermoplasticity due to a curing step, e.g., initiated via heat, UVradiation, electron beam exposure or moisture or other means of curing,leading to the irreversible formation of a crosslinked network ofcovalent bonds. Those materials having lost their initial thermoplasticbehavior are herein also understood as thermoplastic materials.

Alternatively, the absorbent core of the present invention may includeonly one layer. In such an embodiment, the absorbent core includes afirst absorbent layer, the first absorbent layer including a firstsubstrate, absorbent particulate polymer material deposited on the firstsubstrate, and thermoplastic material covering the absorbent particulatepolymer material on the first substrate, the absorbent particulatepolymer material is substantially continuously distributed across theabsorbent particulate polymer material area. Alternatively, the firstabsorbent layer may include a second substrate.

Ink Composition

Embodiments of the present invention include an ink compositioncomprising a water-based ink. The ink composition may include a very lowTg° C. water-based polymer, a binder component, de-tackifier,resolubility agent, and optionally wax, lubricants and/or pigments.Water-based inks useful in the present invention are available fromEnvironmental Inks and Coatings Corporation, Morganton, N.C., under thefollowing code numbers: EH034677 (yellow); EH057960 (magenta); EH028676(cyan); EH092391 (black); EH034676 (orange); and EH064447 (green).

The ink composition includes a very low Tg° C. water-based polymercomponent for providing adhesion to the substrate and improvedcrockfastness.

In one embodiment, the very low Tg° C. polymer is an acrylic latex. Inone embodiment, the very low Tg° C. polymer is from about 5 to about 30wt % of the ink composition, from about 7 to about 15 wt %, about 11 wt% of the ink composition. Combinations of polymers are also useful inthe invention.

While polymers having a very low Tg° C. of about −82° C. are useful inthe present invention, polymers having less than about −80 Tg° C.,polymers having less than about −75 Tg° C., polymers having less thanabout −70 Tg° C., polymers having less than about −60 Tg° C., polymershaving less than about −50 Tg° C., polymers of less than about −42 Tg°C. would also be suitable. Examples of suitable very low Tg° C. polymersuseful in the present invention include acrylics, acrylic latex,styrenated acrylics, ethylene vinyl acetate, ethylene vinyl chloridesand styrene butadiene rubbers (SBR's).

The ink composition may include a binder component. The binder componentmay be from about 20 to about 45 wt % of the ink composition. In oneembodiment of the present invention, the binder component may be apolyurethane dispersion (also known herein as “PUD”). The PUD may be ahigh elongation, high tensile strength, high hardness, water-basedpolymeric dispersion.

The ink composition may include a de-tackifier to improve crockfastness.Suitable de-tackifiers include inorganic materials, with talc beinguseful in one embodiment. Other potential de-tackifiers may includecalcium carbonate, silicas and magnesium stearates. The de-tackifier maycomprise from about 1 to about 4 wt % of the composition.

The ink may include a wax component. The wax component may be from about8 to about 18 wt % of the ink composition. A wax or wax blend may beuseful in the present invention. Appropriate waxes/blends includepolyethylene, carnauba, paraffin, silicone oil, polypropylene,polyolefin blends and combinations thereof.

The ink may include a resolubility agent. The resolubility agent may befrom about 5.0 to about 16.0 wt % of the ink composition. Resolubilityagents useful in the present invention include acrylics solutions anddispersions with a high to medium degree of carboxyl functionality. Inone embodiment, medium acid number, acrylic colloidal dispersionresolubility agents are useful in the present invention.

The ink may include additional waxes and lubricants for detackificationand lowering CoF. The additional wax/lubricant blend may be comprised ofcarnauba (the wax) and silicone oil (the lubricant). In one embodiment,the wax/lubricant blend is from about 1 to about 4 wt % of thecomposition. Waxes useful in the present invention include polyethylene,polypropylenes, high density polyethylene, low density polyethylene andparaffin.

Although not necessary, the ink may include pigments. Examples ofsuitable pigments include, but are not limited to, Blue 15:3, Violet 23,Violet 27, Yellow 14, Yellow 74, Yellow, 83, Yellow 97, Yellow 13, Green7, Red 2, Red 22, Red 48:1, Red 57:1, Red 122, Red 184, Red 238, Red269, Red 49:1, Red 81:1 Red 49:2, Red 166, Red 170, Orange 5, Orange 16,Orange 46, White 7, Black 7, iron oxides, and combinations thereof. Inone embodiment, from about 10 to about 16 wt % pigments are employed,but this may vary according to the specific color and desired density.In one embodiment, pigments in a colloidal dispersion, collectively acolorant, are useful in the present invention.

The ink composition may include surfactants. Surfactants may be presentin the range of from about 1.0 to about 10.0 wt % of the inkcomposition. Surfactants useful in the present invention include dioctylsulfosuccinates, phosphate esters, alkoxylated alcohols, ethoxylateddiols, and mixtures or blends thereof.

In one embodiment of the present invention, an over print varnish (alsoknown herein as “OPV”) may be used. An overprint varnish useful in thepresent invention is available as code number EH012608 fromEnvironmental Inks and Coatings Corporation, or Morganton, N.C. Theoverprint varnish may comprise a very low Tg° C. polymer as describedabove, polyurethane dispersion as described above, a colloidaldispersion as described above, a surfactant as described above, talc asdescribed above, ammonia, and water. The very low Tg° C. polymer may bepresent in the OPV in an amount of from about 3% to about 20%, fromabout 5% to about 15%. The polyurethane dispersion may be present in theOPV in an amount of from about 30% to about 60%. The colloidaldispersion may be present in the OPV in an amount of from about 5% toabout 25%. The surfactant may be present in the OPV in an amount of fromabout 1% to about 15%. Talc may be present in the OPV in an amount offrom about 0.1% to about 10%. Ammonia may be present in the OPV in anamount of from about 0.1% to about 10%. Water may be present in the OPVin an amount of from about 1% to about 50%. Any other componentdescribed in the ink composition may also be useful in the OPV.

The ink composition may be applied to the substrate by any method knownin the art. Specifically, the ink composition may be applied to thesubstrate using ink jet printers, flexographic printing presses, gravureprinting presses, or a combination thereof. The ink composition may beprinted on a number of article components including, but not limited to,the backsheet, topsheet, cuffs, etc. In one embodiment, the inkcomposition is applied to the substrate by flexographic or rotogravureprinting. A metering roll or doctor blade system may be used. In oneembodiment, printing is performed in excess of 500 ft/min, requiringonly minimal adjustment in pH.

The OPV may be applied to the printed substrate by any method known inthe art. The OPV may be applied to the entire substrate, to only theink-printed area, or to any combination thereof. The OPV may be appliedto the substrate using ink jet printers, flexographic printing presses,gravure printing presses, or a combination thereof. In one embodiment,the OPV is applied to the printed substrate by flexographic orrotogravure printing. In one embodiment, the OPV is printed using an80-100% screen printing plate. The OPV may be printed after the inks areprinted and allowed to dry by an inline forced air dryer. The dryertemperature for drying the inks and the OPV may be from about 80° C. toabout 95° C. The OPV may be printed on a number of article componentsincluding, but not limited to, the backsheet, topsheet, cuffs, etc. Ametering roll or doctor blade system may be used. In one embodiment,printing is performed in excess of 500 ft/min, requiring only minimaladjustment in pH.

Untreated polyolefin films and nonwoven substrates have low surfaceenergies. Untreated polypropylene and polyethylene substrates at 20° C.will have low surface energies (usually 30 to 32 dynes/cm). Water at 20°C. has a surface tension of 72.8 dynes/cm compared to 22.3 for ethylalcohol which is often the solvent used in solvent-based inks. As aresult, water-based inks may not adhere or print well on polyolefinfibrous nonwoven substrates and films. In one embodiment, water-basedink systems may require a substrate surface tension of from about 40 toabout 45 dynes/cm in order to provide acceptable adhesion and wetout.Also, the addition of surfactants to lower the surface tension of thewater-based ink or lacquer composition may be useful. However, theaddition of surfactants may cause foaming. Therefore, in one embodiment,the polyolefin substrates may require some amount of surface treatmentin order to accept a water-based ink. In one embodiment, the surfaceenergy of the substrate may be from about 3 dynes/cm to about 10dynes/cm greater than the surface tension of the ink; the surface energyof the substrate may be from about 7 dynes/cm to about 9 dynes/cmgreater than the surface tension of the ink.

Any surface treatment known in the art to may be used in the presentinvention. Surface treatments include, but are not limited to, plasmatreatment, UV treatment, flame treatment, heat treatment, abrasiontreatment, and corona treatment.

In one embodiment, prior to printing the ink composition on thesubstrate, the substrate may be corona treated. Corona treatment is amethod of increasing surface energy on substrates to promote surfacewetting of and adhesion to the substrate when printing, coating orlaminating. The purpose of corona treatment is to increase the surfaceenergy of the substrate web to improve the wettability and adhesioncharacteristics of inks and adhesives to polyolefin films and nonwovensubstrates. Unlike the purely mechanical bond, (as in the case of an inkpenetrating into a porous surface like paper), plastic films andnonwoven substrates may need some means of surface treatment to achieveacceptable chemical bonding with the ink or adhesive.

Corona treatment systems are made of several components designed toapply a high voltage, high frequency electrical discharge to thesubstrate. Corona discharge introduces polar groups into the polymericsurfaces and, as a consequence, increases its surface energy,wettability, and adhesion characteristics. The main chemical mechanismof corona treatment is oxidation. The high voltage ionizes the air inthe air gap creating a corona, which modifies the surface and increasesthe surface energy of the substrate passing over the electricallygrounded roll. The effect is not long lasting and the increase in thesurface energy dissipates within two to six weeks. Use of coronatreatment may raise the surface energy level to value levels of fromabout 38 to about 44 dynes/cm, or from about 40 to about 42 dynes/cm,depending on the Watt density of the corona treatment. Corona treatmentsmay be applied at from about 1.0 to about 10.0 watts per square feet perminute; from about 3.0 to about 5.0 watts per square feet per minute; orabout 4.0 watts per square feet per minute.

Thus, in some embodiments of the present invention, by utilizing surfacetreatments known in the art, including corona treatment mechanisms, thesurface energy of substrates may be increased, thereby improvingcrockfastness. As shown in the data below, corona treatment may beespecially valuable when considering baby oil rub-off resistance.

Test Measurement Methods Crockfastness Measurement Method

The purpose of the crockfastness method is to measure the amount ofcolor transferred from the surface of a printed surface to the surfaceof a standard woven swatch, by rubbing using a rotary verticalcrockmeter. Color transfer (crocking) is quantified using a tristimuluscolor meter (spectrophotomer/colorimeter) and converted to a crock valuescale that ranges from 0=extensive transfer to 5=no transfer of color.

This method is applicable to ink printed nonwovens. Crocking can beperformed on a dry basis or by wetting the standard woven swatch withwater, saline, apple juice, or baby oil. The crocking area should be anarea that is substantially covered with ink.

References: AATCC Test Method 116-2005, Colorfastness to Crocking:Rotary Vertical Crockmeter Method Equipment:

Rotary vertical crockmeter: AATCC Crockmeter, Model CM6; available fromTextile Innovators Corporation, Windsor N.C.Crockmeter cloth: 2 in. by 2 in. square woven swatch; available fromTestfabrics Inc., West Pittston Pa.Tristimulus color meter (spectrophotomer/colorimeter): HunterLab LabscanXE with Universal Software 3.80; available from Hunter AssociatesLaboratory Inc., Reston Va., or equivalent Analytical balance: Toploading, accurate to ±0.001 g; convenient sourceWeighing boats: 3 in. square, disposable polyethylene; convenient sourceVolumetric flask: 100 mL, Class A; convenient source

Reagents:

Purified water Distilled, deionized, or reverse osmotic purified;convenient sourceSodium chloride, ACS reagent grade, convenient source0.9% saline solution prepared by adding 0.908 g±0.001 g of sodiumchloride to 100 mL of purified waterApple juice, Gerber Baby's 1^(st) Foods® apple juice from concentrateBaby oil, Johnson & Johnson's “Johnson Baby Oil® regular unscented babyoil.

Instrument Set-Up and Calibration:

The Hunter Color meter (spectrophotomer/colorimeter) settings are asfollows:

Geometry 45/0 Color Scale CIE L*a*b* Illumination: D65 View Angle 10°Port Size 0.7″ Illumination Area 0.5″Color is reported as L* a* b* values ±0.01 unitsCalibrate the instrument per the vendor instructions using the standardblack and white plates provided by the vendor. Calibration should beperformed each day before analyses are performed. The analyses should beperformed in a temperature and humidity controlled laboratory (23° C.±2°C. and 50%±2% relative humidity, respectively).

Procedure:

-   -   1. All samples and crockmeter cloths are equilibrated at 23°        C.±2° C. and 50%±2% relative humidity for at least 2 hours        before analysis.    -   2. Center a single crockmeter cloth over the port of the color        meter (spectrophotomer/colorimeter) and cover it with the        standard white plate. Take and record the reading. Remove the        crockmeter cloth from the instrument and place it into a        weighing boat with the side just measured (hereafter referred to        as Side A) facing upward.        -   Note: It is important to maintain the orientation of the            crockmeter cloth throughout the experiment, such that all            color measurements and the rubbing are performed on the same            side.    -   3. Using tweezers, remove the crockmeter cloth from the weighing        boat. Place the weighing boat on the analytical balance and tare        the weight.    -   4. Place the crockmeter cloth, Side A up, into the weighing boat        and record its mass to 0.001 g. Calculate 65% of the mass of the        crockmeter cloth to 0.001 g and record as M1.    -   5. Using a disposable pipette, add an amount of the test        solution equivalent to M1 (±5%) to the surface of the crockmeter        cloth, uniformly wetting it.    -   6. Immediately remove the wetted crockmeter cloth from the        weighing dish and secure it to the testing foot of the        crockmeter with Side A facing toward the sample surface.        -   Note: The wetted crockmeter cloth should be handled            carefully and quickly after it is wetted to prevent loss of            moisture before the sample is rubbed.    -   7. Place the sample under the crockmeter foot, such that the        region to be tested is substantially covered with ink and is        directly under, and facing the foot.    -   8. Lower the foot onto the sample. Securely hold the sample in        place and turn the crockmeter handle five full rotations.    -   9. Raise the foot and remove the crockmeter cloth. Place it into        the weighing boat with Side A facing upward. Holding the        crockmeter cloth at its edges, gently smooth its surface.    -   10. Allow the cloths to dry completely (the baby oil will not        dry completely, allow it to dry for at least 8 hours).    -   11. Take the crockmeter cloth and place Side A facing the        orifice of the color meter (spectrophotomer/colorimeter), being        careful to center the rubbed region over the port. Cover it with        the standard white plate. Take and record the reading.    -   12. Repeat steps 2 through 11 for each replicate and each        requested test solution.        -   Note: At least 5 replicates are analyzed using only the 0.9%            saline test solution for each color. The submitter may            request more replicates and/or different test solutions.

Calculations:

Calculate ΔE* as follows from the set of color reading on the untreatedcrockmeter cloth (blank) and the same cloth after crocking (rubbed):

ΔE*=[(L* _(blank) −L* _(rubbed))²+(a* _(blank) −a* _(rubbed))²+(b*_(blank) −b* _(rubbed))²]^(1/2)

If ΔE* is greater than or equal to 12, the crocking value is calculatedas:

Crocking Value=5.063244^((−059532×ΔE*))

If ΔE* is less than 12, the crocking value is calculated as:

Crocking Value=4.0561216^((−0.041218×ΔE*))

Reporting:

Crocking Values are reported as the average of 5 replicates to ±0.1units.

Optical Density/Color Density Measurement Method

The purpose of this method is to provide a procedure for quantitativelymeasuring color and density (ink intensity) of colored (printed andpigmented) materials with a convenient and portable device, theGreytagMacbeth SpectroEye. In this method, the reflective color anddensity of a material is measured with a Hand Held Spectrophotometerusing standardized procedures and reference materials.

Density is a unitless value. Density is a function of the percentage oflight reflected. Density=log_(in) 1/R, where R=Reflectance. The tablebelow shows the relationship of percent reflectance to Density.

% Reflectance Density  100% 0.0 D   10% 1.0 D   1% 2.0 D  0.1% 3.0 D0.01% 4.0 D0-100% solid patches of each ink printed are measured, and the densityvalues recorded and compared to the relative specifications. This willindicate to the press operator whether the amount of ink should beincreased or decreased. As the figure below indicates, ink filmthickness is approximately proportional to optical density.A printing press naturally varies, and a typical tight tolerance fordensity is ±0.05 D. A good demonstration of the normal variation of thepress is to measure the same patch on ten press samples, pulled atone-minute intervals, and record and plot the density values. This showshow density varies with no adjustments to the press.

This method is applicable to materials such as films, nonwovens, andcomposite structures (laminates) that have been colored via printing,tinting, or pigmentation.

This method is applicable to measurements taken by the GretagMacbethSpectroEye spectrodensitometer. Data generated by any other portablespectrophotometers, spectrodensitometers, colorimeters, densitometersare not guaranteed by this method.

Equipment:

Hand Held Spectrophotometer: 45°/0° configuration, hemisphericalgeometry, GreytagMacbeth SpectroEye.Scissors: Convenient typeTissue: Convenient type, without embossing, lotion or brighteners, (e.g.Kimwipes)

White Standard Board: PG2000 Provided by Sun Chemical—Vivitek Division,1701 Westinghouse Blvd., Charlotte, N.C. 28273, Phone: (704)-587-8381

Facilities: The samples and instrument should be kept in an area free ofhigh humidity (75° F. & 50% relative humidity ideally) and corrosivevapors, and the samples should be protected from contamination by dirtor lint.Set up the color meter as follows:

-   -   Physical Filter: None    -   White Base: Abs    -   Observer: 2°    -   Density Standard: ANSI T    -   Illumination: C        NOTE: Ensure that the spectrophotometer is set to read L* a* b*        units and not Hunter Lab units

Procedure:

-   -   1. Select a sample region for analysis. For printed film and        nonwovens carefully place 1 ply of the 100% coverage area sample        over the PG2000 white standard board.    -   2. Place the Macbeth SpectorEye aperture over the sample and        confirm that only sample material can be viewed within the        instruments aperture window.    -   3. Toggle through the measurement menu to Read and Record the        color (L*, a*, and b*) and Density values for each sample.

Calculations:

-   -   1. For each ink, measure and record density readings.    -   2. For each measurement set, use at least three recordings to        calculate and report the average and a standard deviation.

Reporting: Density values are to be reported to the nearest 0.01 units

Leachability Measurement Method Equipment:

Tristimulus color meter (spectrophotomer/colorimeter): HunterLab LabscanXE with Universal Software 3.80; available from Hunter AssociatesLaboratory Inc., Reston Va., or equivalent Glass Liquid Cup Assembly(Part LSXE-SC-ASSY, HunterLab) consisting of a port insert, 2.5″ glasscup, black spacer ring, white ceramic disk, and opaque coverOrbital rocker: convenient source25 mL glass screw top vialsLeachability is tested in 0.9% w/w saline, 100% isopropanol, clear babyoil

Instrument Set-Up and Calibration:

The Hunter Color meter (spectrophotomer/colorimeter) settings are asfollows:

Geometry 45/0 Color Scale CIE L*a*b* Illumination: D65 View Angle 2°Port Size 1.75″ Illumination Area 1.0″

Calibrate the instrument per the vendor instructions using the standardblack and white plates provided by the vendor. Calibration should beperformed each day before analyses are performed.

Extraction:

-   -   1. Cut three 6 by 6 cm squares of the printed material.    -   2. Fold all three squares and place into a 25 mL vial, add 15 mL        of test solution, seal and shake vigorously until the specimens        are wetted and submerged into the test solution.    -   3. Extract the sample at 37° C. (±2° C.) for 12 hours with        moderate mixing on the orbital rocker.    -   4. A blank test solution, with no printed specimen, is treated        in the same fashion for comparison.

Measurement:

-   -   1. Insert the spacer ring into the sample cup.    -   2. Fill the cup with the extract (or blank) such that the liquid        is just above the top of the spacer ring.    -   3. Place the ceramic disk on top of the spacer ring and set the        assembled sample cup on top of the sample insert.    -   4. Cover the sample cup with the opaque cover.    -   5. Take reading for L* a* b* values and record to ±0.01 units    -   6. Repeat for the blank test solution.

Calculation:

ΔE*=[(L* _(blank) −L* _(extract))²+(a* _(blank) −a* _(extract))²+(b*_(blank) −b* _(extract))²]^(1/2)

Leachability Colorfastness Rating=5.0+0.0045(ΔE*)²−0.2553(ΔE*)

-   -   Leachability Colorfastness Rating should be reported as the        average of a minimum of 3 replicates to ±0.01 units.

Data and Analysis

Crockfastness and color density data generated relative to the inkcompositions of the present invention is as follows:

INK ONLY PRINTED NONWOVEN Dry Synurine Water Apple Juice Baby Oil CFRCFR CFR CFR CFR Density Ink Sig- Sig- Sig- Sig- Sig- Sig- Color Xbar maXbar ma Xbar ma Xbar ma Xbar ma Xbar ma Yellow 3.0 0.1 4.1 0.2 4.3 0.14.3 0.1 3.1 0.2 0.53 0.02 Magenta 3.4 0.1 3.9 0.1 3.9 0.2 4.0 0.1 2.80.1 0.49 0.04 Cyan 3.8 0.1 4.4 0.1 4.5 0.1 4.2 0.1 3.1 0.1 0.56 0.03Black 4.0 0.1 4.5 0.2 4.4 0.1 4.6 0.1 3.1 0.1 0.56 0.05

INK + OPV (NO CORONA) PRINTED NONWOVEN Dry Synurine Water Apple JuiceBaby Oil CFR CFR CFR CFR CFR Density Ink Sig- Sig- Sig- Sig- Sig- Sig-Color Xbar ma Xbar ma Xbar ma Xbar ma Xbar ma Xbar ma Yellow 4.0 0.1 4.40.1 4.5 0.1 4.4 0.1 3.4 0.1 0.52 0.05 Magenta 4.3 0.1 4.4 0.1 4.6 0.14.4 0.1 3.9 0.1 0.49 0.02 Cyan 4.6 0.1 4.8 0.1 4.9 0.1 4.4 0.1 4.0 0.10.56 0.03 Black 4.6 0.1 4.8 0.1 4.8 0.1 4.7 0.1 4.0 0.1 0.56 0.04

INK + CORONA (NO OPV) PRINTED NONWOVEN Dry Synurine Water Apple JuiceBaby Oil CFR CFR CFR CFR CFR Density Ink Sig- Sig- Sig- Sig- Sig- Sig-Color Xbar ma Xbar ma Xbar ma Xbar ma Xbar ma Xbar ma Yellow 2.6 0.2 3.30.4 3.2 0.4 4.3 0.1 4.1 0.1 0.50 0.02 Magenta 2.8 0.4 2.6 0.1 2.6 0.23.2 0.2 4.1 0.2 0.57 0.03 Cyan 3.6 0.1 3.2 0.1 3.5 0.4 3.6 0.4 4.2 0.10.64 0.03 Black 3.8 0.1 3.1 0.1 2.9 0.1 3.3 0.2 3.6 0.2 0.48 0.06

INK + CORONA + OPV PRINTED NONWOVEN Dry Synurine Water Apple Juice BabyOil CFR CFR CFR CFR CFR Density Ink Sig- Sig- Sig- Sig- Sig- Sig- ColorXbar ma Xbar ma Xbar ma Xbar ma Xbar ma Xbar ma Yellow 4.2 0.2 3.5 0.23.8 0.2 4.0 0.2 4.2 0.2 0.58 0.06 Magenta 3.7 0.3 3.3 0.3 3.2 0.2 3.60.2 4.0 0.2 0.62 0.02 Cyan 4.0 0.3 3.3 0.1 3.4 0.5 3.6 0.1 3.9 0.1 0.710.05 Black 4.2 0.1 3.6 0.2 3.4 0.1 3.9 0.1 3.6 0.1 0.57 0.02

As shown by the data above, the ink compositions of the presentinvention are useful in improving crockfastness. Specifically, thecrockfastness values of the present invention are greater than about2.5, greater than about 3.0, greater than about 3.1, greater than about3.2, greater than about 3.3, greater than about 3.4, greater than about3.5, greater than about 3.6, greater than about 3.7, greater than about3.8, greater than about 3.9, greater than about 4.0, greater than about4.1, greater than about 4.2, greater than about 4.3, greater than about4.4, greater than about 4.5, greater than about 4.6, greater than about4.7, greater than about 4.8.

Also, as shown by the data above, the ink compositions of the presentinvention are useful in improving color density. Specifically, the colordensity values of the present invention are greater than about 0.40,greater than about 0.45, greater than about 0.48, greater than about0.50, greater than about 0.52, greater than about 0.55, greater thanabout 0.57, greater than about 0.60, greater than about 0.62, greaterthan about 0.64, greater than about 0.68, greater than about 0.70.

Typically, screen values, also known as % dot coverage, impact thecrockfastness rating and color density of the printed image on thesubstrate. Generally, the higher the % screen value, the lower thecrockfastness rating. Conversely, the higher the % screen value, thehigher the optical density, as the thickness of the printed inkthickens. Eventually, however, the density values may plateau. Inks ofthe present invention may be printed at slightly greater than 0% screenvalues (clear/white), up to 100% screen value (maximum color), or at any% screen value in between.

Typically, improved color density for a given ink results in a reductionin the ink adhesion and crockfastness of the ink. The rate of loss ofcrockfastness versus the increase in optical density is defined as theCrockfastness-Loss-to-Density-Ratio (CLDR). CLDR is a non-linearrelationship that is further quantified by the following equation fordry and hydrophilic wetting agents: CLDR=δY/δX=−(4.46X+0.73), wherein Xis the color density and Y is the crockfastness.

For baby oil wetted printed nonwovens, CLDR=δY/δX=−1.61, wherein X isthe color density and Y is the crockfastness.

The present invention is directed to minimizing the CLDR to improve inkadhesion. Oftentimes, the CLDR of inks has a value of less than about−0.6.0. In some embodiments of the present invention, the CLDR has anegative value of from about −1.0 to about −6.0; from about −1.0 toabout −3.0; from about −2.0 to about −3.0.

In one embodiment, the baby oil crockfastness for inks in the presentinvention are less sensitive to increases in the optical density. Thisis a desirable characteristic given the broad, frequent, and acceptableuse of baby oil by caregivers to treat the skin of babies and the needfor improved baby oil resistance of the ink printed images. In someembodiments of the present invention, the CLDR relative to baby oil hasa value of from about −1.0 to about −3.0; from about −1.0 to about −2.0.

Oftentimes, pigments tend to solubilize when exposed to certain chemicalsubstances. This is known as “leachability” and may also be referred toas “pigment bleed.” In diaper usage, many current printing inks mayreact with or be leached by common fluids such as water, salinesolution, baby oil, etc. that may come into contact with a baby's skin.These fluids may cause the ink-printed image to rub off, smear, transferto the skin, transfer to furniture and/or other surfaces. In oneembodiment of the present invention, once the ink composition has beenprinted and dried onto the substrate, leachability improves. As the databelow indicate, in one embodiment of the present invention, Cyan andBlack exhibit no visible pigment leaching by any of the chosensolutions. Thus, in one embodiment of the present invention, theleachability of the ink composition is less than about 10, less thanabout 5, about 0.

Leachability Results (ΔE Color Change of Fluid) Ink Water SalineSolution Baby Oil Colors Ink Only Ink + OPV Ink Only Ink + OPV Ink OnlyInk + OPV Yellow 0.0 0.0 0.0 0.0 9.4 7.4 Magenta 0.0 0.0 4.4 3.2 0.0 0.0Cyan 0.0 0.0 0.0 0.0 0.0 0.0 Black 0.0 0.0 0.0 0.0 0.0 0.0

Colorfastness Results Ink Water Saline Solution Baby Oil Colors Ink OnlyInk + OPV Ink Only Ink + OPV Ink Only Ink + OPV Yellow 5.0 5.0 5.0 5.03.0 3.4 Magenta 5.0 5.0 4.0 4.2 5.0 5.0 Cyan 5.0 5.0 5.0 5.0 5.0 5.0Black 5.0 5.0 5.0 5.0 5.0 5.0

All documents cited in the Detailed Description of the invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this written document conflicts with any meaningor definition of the term in a document incorporated by reference, themeaning or definition assigned to the term in this written documentshall govern.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm”.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and the scope of the invention. It istherefore intended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An ink-printed substrate, comprising: a. asubstrate; b. a water-based ink composition printed on the substrate,forming a water-based ink printed area; c. an overprint varnishcomprising a very low Tg° C. water-based polymer component and a binder;wherein the ink composition comprises cyan having an average cyan colordensity of at least about 0.56 or greater.
 2. The ink-printed substrateof claim 1, wherein the substrate is one of the group of a non-woven, afilm, a polyolefin web, a fibrous polyolefin web, a cellulosic web, anelastomeric web or combinations thereof.
 3. The ink-printed substrate ofclaim 1, wherein the substrate exhibits a low surface tension.
 4. Theink-printed substrate of claim 1, wherein the substrate is at least oneof hydrophobic, apolar, or inert.
 5. The ink-printed substrate of claim1, wherein the water-based ink composition comprises a very low Tg° C.water-based polymer component.
 6. The ink-printed substrate of claim 1,wherein the water-based ink composition further comprises a binder. 7.The ink-printed substrate of claim 1, wherein the overprint varnish isapplied to the water-based ink printed area.
 8. The ink-printedsubstrate of claim 1, wherein the ink printed substrate comprises anaverage crockfastness of at least about 3 or greater.
 9. The ink printedsubstrate of claim 1, wherein the substrate is pretreated with a surfacetreatment selected from the group consisting of plasma treatment, UVtreatment, flame treatment, heat treatment, abrasion treatment, andcorona treatment.
 10. A disposable absorbent article, comprising: atopsheet, a backsheet, and an absorbent core between the topsheet andthe backsheet, the backsheet comprising the ink-printed substrate ofclaim
 1. 11. An ink-printed substrate, comprising: a. a substrate; b. awater-based ink composition printed on the substrate, forming awater-based ink printed area; c. an overprint varnish comprising a verylow Tg° C. water-based polymer component and a binder; wherein the inkcomposition comprises yellow and wherein yellow has an average yellowcolor density of at least about 0.50 or greater.
 12. The ink-printedsubstrate of claim 11, wherein the substrate is one of the group of anon-woven, a film, a polyolefin web, a fibrous polyolefin web, acellulosic web, an elastomeric web or combinations thereof.
 13. Theink-printed substrate of claim 11, wherein the substrate exhibits a lowsurface tension.
 14. The ink-printed substrate of claim 11, wherein thesubstrate is at least one of hydrophobic, apolar, or inert.
 15. Theink-printed substrate of claim 11, wherein the water-based inkcomposition comprises a very low Tg° C. water-based polymer component.16. The ink-printed substrate of claim 1, wherein the ink printedsubstrate comprises an average crockfastness of at least about 2.6 orgreater.
 17. A disposable absorbent article, comprising: a topsheet, abacksheet, and an absorbent core between the topsheet and the backsheet,the backsheet comprising the ink-printed substrate of claim
 11. 18. Anink-printed substrate, comprising: a. a substrate; b. a water-based inkcomposition printed on the substrate, forming a water-based ink printedarea; c. an overprint varnish comprising a very low Tg° C. water-basedpolymer component and a binder; wherein the ink composition comprisesmagenta and/or black and an average color density of at least about 0.48or greater.
 19. The ink-printed substrate of claim 18, wherein thesubstrate is one of the group of a non-woven, a film, a polyolefin web,a fibrous polyolefin web, a cellulosic web, an elastomeric web orcombinations thereof.
 20. The ink-printed substrate of claim 18, whereinthe ink printed substrate comprises an average crockfastness of at leastabout 2.6 or greater.